1. Field of the Invention
This invention relates in general to apparatus for latching and unlatching a load from a sling and, more particularly, to such apparatus having a locking structure and one or more safety devices activated by the application of a force caused by the lifting of the load.
2. Prior Art
In construction and other commercial or industrial environments it is necessary to move a load from one place to another place. This movement is facilitated by the use of cranes having a lifting line to which slings can be attached for securing the load to the lifting line. Various devices used to latch and unlatch a load from these slings are well known in the prior art. In the design of these devices it is necessary to consider the multiple uses to which they will be employed, including the handling of various shape, size, and type loads. In addition these devices must not only be simple to operate, but only permit such operation in a manner that minimizes the risk that a load would be unlatched from the lifting line prematurely or conducted in a manner that may otherwise cause harm to personnel working around the site. Although some of these design criteria have been addressed by the prior art, there remains a need for their improvement.
Many construction sites have multiple tasks being performed by different personnel at the same time. Thus the different personnel are more likely to be focused on the tasks to which they have been assigned, and may not be aware of the other activities at the site. In addition the noise at these sites may be at a level that makes it difficult to provide an audible warning to personnel if something has mistakenly occurred, such as the premature release of a load from a lifting line.
Another problem relates to the manner in which the load is released from the latching device. It is the common practice to utilize a secondary line that is operatively attached to the latch which when pulled releases the latch and permits the load to be released from the lifting line. Such secondary lines in addition to being cumbersome are more susceptible to being inadvertently pulled before it is desired that a load be released from the lifting line. This inadvertent action can result not only in harm to surrounding personnel, but also damage to the load.
To minimize risk with the prior art devices, it is in many instances required that ground crews and other machinery slow their operations or come to a stand-still while the task of moving the load is completed. This adds both time and cost to the operation or construction occurring at the site.